Extraction and separation of strategic precious Ag from low-grade Mn-Ag ores in China: A short review of co-leaching and selective leaching processes

Silver-bearing manganese ore (Mn-Ag ore) is an important resource for the extraction of the precious metal Ag. However, the efficient and economical utilization of low-grade Mn-Ag ore poses challenges due to its polymetallic co-occurrence, complex associated mineral structures, and lower Ag grade compared to an industrial Ag grade of 80 g/t. In contrast, the Ag grade of commercially viable concentrate, achieved through physicochemical beneficiation, generally exceeds 1000 g/t. This work briefly discusses the metallogeny and resource characteristics and the processing technologies of Mn-Ag ore to produce high grade Ag concentrates. Based on the metallogeny characteristics of Mn-Ag deposits, this work delves into the challenges and difficulties in the physical separation of Ag and Mn. By regulating the differences in the chemical properties of Mn and Ag constituents, chemical beneficiation processes, including unit operations of pyrometallurgy and hydrometallurgy, result in favorable Ag and Mn enrichment and separation. The chemical principles, technical parameters, Mn-Ag separation efficiency, and advantages and disadvantages of chemical beneficiation (blast furnace smelting, chlorination roasting, one-step leaching, and two-step leaching) were systematically summarized and discussed. This work can provide theoretical and technical guidance for the effective treatment of low-grade Mn-Ag ores.